Windows buildsystem

Some improvements to the windows build system.

Important improvements

• Dependencies are now selected using globbing expressions, so the build should be more robust with respect to future package updates.
• I added a script which allows to list required dependencies which we need to install.
  It can also check for missing / unused dependencies in the installed target (especially useful for CI).

I had considered to determine the libraries which need to be installed fully dynamical but had to discard the idea as impractical:

• We have to compile Inkscape before we can determine dependencies, so the files that are part of the install target will only ever be known at the end of the build process, not when initially running cmake.
• Determining the dependency tree takes some time - time we do not want to waste whenever building the project
• It's a bit of a chicken-and-egg problem - we only ever know what dependencies we really need after actually installing most of the project (i.e. python extensions, gdk-pixbuf loaders, ...)